Accessory drive for free-piston units



March 21,- 1950 J, HOOKER 2,501,053

ACCESSORY DRIVE FOR FREE-PISTON UNITS Filed March 1:2, 1948 MYIWIIIII/II Patented Mar. 21, 1950 ACCESSORY DRIVE FOR FREE-PISTON UNITS Ralph J. Hooker, Hamilton, Ohio, assignor to United Aircraft Corporation, East Hartford, Conn, a corporation of Delaware Application March 12, 1943. Serial No. 14,468

9 Claims. (Cl. ma -4s) This invention relates to free-piston units and particularly to an arrangement for providing a rotating motion for driving accessories for the unit.

The usual free-piston unit has opposed reciprocating piston elements which are free to move within the engine-and-compressor cylinders and are caused to move synchronously by a linkage which interconnects the pistons and which has, in general, an interconnecting element having an oscillatory motion. This type of free-piston unit 1 has no crankshaft, and, accordingly, no rotating part. It is advantageous to have a rotary drive which might be used, for example, for circulating cooling fluid through the engine piston or around the engine cylinders or for supplying lubricant or fuel to the unit. A feature of the invention is such a drive actuated by the unit and so arranged as to rotate continuously in one direction during operation of the unit.

In freeoiston units operating at high capacity, the pistons have a high frequency of reciprocation and the interconnecting linkage has the same high frequency. It has been proposed to operate a hydraulic pump in response to the piston reciprocation to provide fluid under pressure, such as lubricant or fuel. At the high frequencies now obtainable in these units, the hydraulic pump becomes inoperative by reason of the inertia of the valve mechanism and of the liquid that is cyclically accelerated. To overcome this difficulty, a feature of the invention is an oscillating centrifugal pump which utilizes the inertia of the fluid and which is constructed to be actuated by the synchronizing linkage. Another feature is the use of a hydraulic motor adapted to be driven by the fluid under pressure provided by the centrifugal pump. One feature of the invention is an arrangement of the pump and motor is such a manner that the fluid used is circulated in a substantially annular ath.

A feature of the invention is an oscillating vane type of pump cooperating with a vane type motor similar to a turbine runner and associated with stationary guide vanes which direct the fluid from.

the pump against the motor vanes.

Other objects and advantages will be apparent from the specification and claims, and from the accompanying drawing which illustrates anembodiment of the invention.

Fig. 1 is diagrammatic sectionalviewthrough the free-piston unit showing the rotary drive in elevation.

Fig. 2 is a sectional view through the hydraul pump and motor of the rotary drive.

2 Fig. 3 is a sectional view substantially along the line 3-3 of Fig. 2.

Fig. 4 is a sectional-view substantially along the line 4-4 of Fig. 2. showing the stator vanes and the vanes on the motor.

The free-piston unit combines an engine cylinder 2, having opposed reciprocating pistons 4 and 6 therein, to which compressor pistons 8 and in are integrally connected. The compressor pistons 8 and I0 reciprocate in compressor cylinders i2 and i4 which may form an integral part of the surrounding housing It for the unit. sleeves l8 and 20, attached to the engine and compressor pistons, complete the reciprocating piston assemblies. The sleeves reciprocate over air spring pistons 22 and 24 and form, with said pistons, air springs which move the opposed piston assemblies toward each other on the compression stroke.

The piston assemblies are moved apart by the burning of fuel injected into the engine cylinder as by fuel nozzle 28. The assemblies are maintained at equal but varying distances from the center of the engine cylinder by a linkage which includes projecting rods 28 and 30 extending from the compressor pistons 8 and i0 and meshing with a pinion 32. It will be apparent that the pinion 32 oscillates when the piston assemblies reciprocate within the respective cylinders.

An intake manifold 34 surrounds the unit, the outer housing It forming the outside wall of the manifold, and conducts air to inlet valves 36 in the outer ends of the compressor cylinders. The air compressed in the cylinders is discharged through valves 38 into chambers 40 and 42 at opposite ends of the unit. These chambers are interconnected by a duct 44 which also communicates with a chamber 46 surrounding the engine cylinder. From the chamber 46 the air enters the engine cylinder through ports 48. Exhaust ports 50 permit the exhaust gas to escape from the engine cylinder into the exhaust pipe impeller, to force fluid outwardly against a cap 62, forming a part of the housing 58. The cap forms the outer part of an annular path 64 through which the fluid is circulated, the center ahapedtube It carriedbyvanesiton'thecap O2 and located adjacent to the free radial edges of the impeller vanes I. This tube It causes the fluid to be pumped by the impeller vanes into the cap which redirects the fluid inwardly to the fluid motor.

directins vanes 08 in The cap 62 supports the the fluid path, and the vanes are so arranged as to direct the flow inwardly with a tangential component or circumferential direction of flow, as shown in Fig. 4, against the vanes III on the rotor 12, constituting the vane type fluid motor thereby causing the rotor 12 to turn. The rotor has a shaft It from which the accessories may be driven. It will be apparent that the rotor or motor runner 12 rotates continuously in one direction since the fluid set in motion by the impeller vanes It is directed at the same angle against the rotor vanes regardless of which direction the impellers it is moving. The rotor vanes II are preferably so arranged as to take advantage of all of the energy of the pump fluid and in this way will assure an adequate supply of power for the accessory drive.

The inner part of the annular path for the fluid, which, as will be apparent, is continuously circulated by the impeller vanes CI, is defined by curved surfaces It and It on the impeller 56 and rotor 12, respectively. A supply of fluid for the accessory drive may be provided through the shaft 54 from a pipe ll communicating with a groove 82 in the bearing 84 which supports the shaft and which may be a part of the housing ll. Fluid from the groove 82 enters the shaft through radial passages it and thence through an axial passage 88 to other radial passage 80 communicating with the annular fluid space. The cap 62 may be provided with vents 92 by which the accessory drive may be rendered inoperative by cutting off the supp y of fluid through the pipe 80.

It is to be understood that the invention is not limited to the specific embodiment herein illustrated and described, but may be used in other ways without departure from its spirit as defined by the following claims.

I claim:

1. In a fluid drive, an oscillating centrifugal pump, a rotary vane type motor, and a housing having stationary vanes therein for guiding the fluid against the motor vanes, said housing being constructed to define a fluid path from the discharge of the pump through the stationary vanes to the motor inlet.

2. In a fluid drive, an oscillating centrifugal pump, a rotary vane type motor, and a housing having stationary vanes therein for guiding the fluid against the motor vanes, said housing being constructed to define a fluid path from the discharge of the pump through the stationary vanes to the motor inlet, the pump and motor being constructed to form a path for fluid from the motor discharge to the pump inlet.

3. In a fluid drive, an oscillating centrifugal pump including a disc having a row of radial vanes on one side surface thereof, a rotary vane type motor including a disc having its axis substantially coincident with the axis of the pump disc and having a row of vanes on the surface adjacent to the pump disc, and a housing having stationary vanes therein for guiding the fluid from the pump against the motor vanes, said housing extending around said discs to define a fluid path from the outer surfaces of the pump vanes to the outer surfaces of'the motorwanes with the stationary vanes located in saidpath.

4. In a fluid'drive, an oscillating centrifugal pumpincludingadischavingarowofradlal vanes on one side surface thereof, a rotary vane type motor including a disc having its axis substantially coincident with the axis of the pump disc and having a row of vanes on the surface adiacent to the pump disc, and a housing having stationary vanes therein for guiding the fluid from the pump against the motor vanes, said housing extending around said discs to deflne a fluid path from the outer surfaces of the pump vanes to the outer surfaces of the motor vanes with the stationary vanes located in said path, the pump and motor discs being constructed to form a path for fluid from the motor discharge to the pump inlet.

5. In a fluid drive, an oscillating centrifugal pump including a disc having a row of radial vanes on one side surface thereof, a rotary vane type motor including a disc having its axis substantially coincident with the axis of the pump disc and having a row of vanes on the surface adjacent to the pump disc, and a housing having stationary vanes therein for guiding the fluid from the pump against the motor vanes, said housing extending around said discs to define a fluid path from the outer surface of the pump vanes to the outer surfaces of the motor vanes with the stationary vanes located in said path, said stationary vanes being constructed and arranged to impart a circumferential direction of flow to the fluid delivered by the pump.

6. In a fluid drive, an oscillating centrifugal pump including a disc having a row of radial vanes onone side surface thereof, a rotary vane type motor including a disc having its axis substantially coincident with the axis of the pump disc and having a row of vanes on the surface adjacent to the pump disc, and a housing having stationary vanes therein for guiding the fluid from the pump against the motor vanes, said housing extending around said discs to define a fluid path from the outer surface of the pump vanes to the outer surfaces of the motor vanes with the stationary vanes located in said path, said housing also carryin a ring located between the motor vanes and pump vanes to define the inner wall of the fluid passage for directing fluid from the pump vanes over the stationary vanes and onto the motor vanes.

'1. In a free-piston unit, opposed pistons, a cylinder in which said pistons reciprocate, and a linkage connecting said pistons, a part of said linkage having oscillatory motion, in combination with a rotary shaft, and means for driving the rotary shaft from said unit including a centrifugal pump connected to the linkage and a rotary fluid motor connected to said shaft and driven by fluid under pressure from said pump.

8. In a free-piston unit, opposed pistons, a cylinder in which said pistons reciprocate, and a linkage connecting said pistons, a part of said linkage having oscillatory motion, in combination with a rotary shaft, and means for driving the rotary shaft from said unit including a centrifugal pump connected to the linkage and a rotary fluid motor connected to said shaft and driven by fluid under pressure from said pump, and a housing surrounding said pump and motor and being constructed to form a path for fluid from the pump discharge to the motor inlet.

9. In a free-piston unit, opposed pistons, a cylinder in which said pistons reciprocate, and

5 6 a linkage connecting said pistons, a part oi said linkage having oscillatory motion, in combina- REFERENCES CITED tion with a rotary sh ft, and an for driving The following references are of record in the the rotary shaft from said unit including fa file of this Patentr centrifugal pump' connected to the linkage and 5 UNITED STATES PATENTS a rotary fluid motor connected to said shaft and driven by fluid under pressure from said pump, Number IfTame Date and a housing surrounding said pump and motor 1,199,364 Fottmger sept- 1916 and being constructed to form a path for fluid 1,680,017 1928 from the pump discharge to the motor inlet, 10 2296-695 zworykm Sept 1942 said housing havin stationar vanes arranged F R N PATENTS tto impart a tangential velocity to the fluid and N t te located in the fluid path from the pump disumber W Da charge and t motor inlet. Great Britain 19 5 RALPH J. HOOKER. 15 

